Alternating current bell



ly 1935. J. N. VMOYFWIGGAN I ALTERNAT ING CURRENT BELL Filed April 29, 1951 INVENTOB JZV/ffflfi 7W 7201 296171,

ATTORNEY Patented July 2,1935

(Granted under the act of March 3, 1883; as.

amended April 30,1928; 370 0.; G. 757) This invention relates broadly to signaling, and more particularly to a resonant reed device for operation in signaling circuits employing analternating 'or an intermittent sourcerof,v electromotive force. i I f One of the objects of this-invention is to pro' Vide an electrically excited resonant reed device of simplified'design which is of rugged construction and capable of handling a relatively large amount of power and yet is electrically sensitive.

Another object of the invention is to provide a moisture proof vibrating reed device particularly suitable for marine use, in which the e'lectrical windings are encased and in which the vibrating reed is actuated on the exterior of the case by means of magnetic paths through the case.

Another object of the invention is to provide an electrically excited'reed device capable of being vibrated by a source of alternating or pulsating electro-motive force at the same frequency as the source of electromotive force or any-submultiple or harmonic thereof.

Another object of the invention is to provide an electrically excited vibrating device requiring no circuit making and breaking device, and one that may be adjusted to operate from sources of potential of various values.

Another object of the invention is to provide an alternating current excited vibrating device suitable for actuating at a characteristic. frequency the striker of an electric bell or buzzer orfor vibrating a tympanum or the like. H

Other and further objects of the invention will be understood from the specification hereinafter following by reference to the accompanying drawing forming a part of the specification, in which:

Figure 1 is a view partially in cross section showing the invention as embodied in a gong bell; I Figures 2 and 3 diagrammatically illustrate modifications of the coil structure;

Figure 4 is a perspective view of the vibrating reed element.

Referring to the drawing in detail, the bell case which is preferably of non-magnetic material is represented by reference character I. The cover of non-magnetic material is shown at 2. The bell gong 3 is mounted on a post I 4 extending from the center of cover 2. A U- shaped laminated soft steel core is shown at 4 I mounted to the cover 2 by means of magnetic metal screws 5. The core 4 need not, however,

be laminated in small low frequency bells. Carried on the laminated steel core 4 is one or more exciting coils 6 to whose terminals a-d' thepul eating or alternating source of electromotive force is connected. Numeral 1 represents the vibrating reed element which is attached at; one end to the upstanding boss [5- provided on the cover. and magnetically. connected to one end oftheu shaped laminated'core' 4. by means of the screw 5 extending through u aperture ill and through a hole provided in the boss l5. The free end of the reed l is placed adjacent to the other end of the laminated core 4 which may if desired be polarized. The reed I is provided near its fixed end with a portion 8 of reduced cross section about which the free end pivots.

larged portion I! constituting the striker. The

gong 3 is provided with a lug l2 arranged adjacent to the striker II to be struck thereby when the reed I is set into vibration. Referring to the modification shown in Figures 2 and 3,6 is a second winding similar to winding 6 arranged on one of the legs of the core 4. In Figure Zthis additional winding is shown connected in series with the winding 6 while in Figure 3 this winding is connected in parallel with winding 6. Other and additional windings similar to 6' of selected sizes may be provided for the other leg of the core or there may be several such windings oneach leg thereof connected in series, parallel or in series parallel either aiding or in part opposing each other. By making the windings in sections as 6, 6", etc., the impedance may be regulated to adapt the device for use with various voltages and frequencies or to tune the device. to electricalresonance with an associated condenser l3 connected in'parallel with the windings. Similarly condensers can be connected in parallel with thewindings 6 and 6' in Figures 1 and 3. v

The electrical energy supply which is connected at aa may have an alternating electrcmotive force of pure sine wave form which is most desirable. However, in many cases, it may be distorted by harmonics and this distortion may be increased by a counter electromotiveforce due to the reaction of the vibrating reed I on the magnetic field. The effects of these harmonics can be reduced by placinga condenserin parallel with the terminals of the electromagnet. The condenser should be of a sizeto electrically tune the system to the fundamental frequency or one of the harmonics of the applied alternating electromotive force.

This increases the sensitivity and efiiciency of the device.

Figure 4 shows the mechanically resonant element 1 which is so proportioned as to have a' period of vibration equal to the frequency of the alternating potential impressed at aa or some submultiple or harmonic thereof. The frequency of this reed may be changed or adjusted by filing oiT a part of the striker at l I to increase the frequency or the frequency may be decreased by sweating, soldering or otherwise attaching thereto additional metal. The frequency may be further changed by increasing the depth of the cut of the portion of reduced section at 8 or by selecting a reed of different dimensions or modulus of elasticity.

The reed 1 is preferably adjusted to vibrate directly in proportion to the frequency of the impressed electromotive force. The magnetic flux resulting in the core 4 vibrates the reed at the greatest amplitude and-efficiency when these conditions exist. With an *unpolarized core and with a EEO-cycle source of potential impressed at M I i the need should be tuned to vibrate at a rate of and accompanying drawing comprehend only the general and preferred embodiment of this invention, and that various changes in construction, proportion and arrangement of parts may be made within the scope of the appended claims, and without sacrificing any of the advantages of this invention.

The herein described invention may be manufactured and used by or for the Government of the United States for governmmtal "purposes Without the payment to me of any royalties thereon or therefor.

Having thus described the invention, what I claim is:

An alternating current bell comprising a casing, a non-magnetic cover for said casing carrying an upstanding post and a boss thereon, a U-shaped magnetic core attached to said cover on the side thereof opposite to said post and boss by magnetic screws one of which extends through said boss, a gong mounted on said post, a reed fixedly mounted at one end on said boss by one I magnetic core.

JAMES N. MCTWIGGAN. 

